The goal of the proposed research is to understand the regulatory mechanisms that govern neuronal cell type specification through the basic helix-loop-helix (bHLH) transcription factor, Atoh1. How d!1 neurons in the dorsal neural tube and granule cells in the cerebellum are encoded by Atoh1 remains undefined due to the lack of known Atoh1 targets. This study will focus on identifying transcription factors that are Atoh1 targets and uncover the Atoh1 cis-regulatory code that specifies neuronal cell types. The long term goal is to understand the molecular mechanisms of how neuronal bHLH transcription factors regulate neuronal cell type specification possibly leading to the identification of therapeutic targets for neurodegenerative diseases, brain and spinal cord injuries, and neuronal cell-derived cancers. The specific aims are:1. Identify Atoh1 targets and determine functionally important regulatory regions of these targets. Microarray experiments have identified transcripts enriched in Atoh1-lineage cells. Downstream targets of Atoh1 will be identified from a candidate list of transcription factors and their regulatory regions tested for proper expression of a reporter gene in chick and transgenic mouse assays. Direct targets of Atoh will be identified by chromatin immunoprecipitation (ChIP) approaches.2. Determine a cis-regulatory code by which Atoh1 specifies neurons. Regulatory regions of direct Atoh1 targets will be probed for an Atoh1 consensus binding site and regulatory regions of Atoh1 targets will be examined for common transcription factor binding sites or DNA sequence motifs using bioinformatics analyses. Candidate regulatory codes will be functionally tested by mutation in the chick or transgenic mouse reporter assays. Regulatory codes will be used to further identify targets of Atoh1 through iterative cycles of Aims 1 and 2. I am trying to understand how neurons form at their most basic level. My research may lead to discoveries in understanding how we can therapeutically restore working nerves in people with brain and spinal cord injuries, neurodegenerative diseases such as Alzheimer's or Parkinson's disease, or pediatric brain tumors.